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-rw-r--r--tools/perf/util/arm-spe.c37
1 files changed, 34 insertions, 3 deletions
diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c
index da379328442c..5c5b438584c4 100644
--- a/tools/perf/util/arm-spe.c
+++ b/tools/perf/util/arm-spe.c
@@ -434,12 +434,36 @@ static int arm_spe_sample(struct arm_spe_queue *speq)
static int arm_spe_run_decoder(struct arm_spe_queue *speq, u64 *timestamp)
{
struct arm_spe *spe = speq->spe;
+ struct arm_spe_record *record;
int ret;
if (!spe->kernel_start)
spe->kernel_start = machine__kernel_start(spe->machine);
while (1) {
+ /*
+ * The usual logic is firstly to decode the packets, and then
+ * based the record to synthesize sample; but here the flow is
+ * reversed: it calls arm_spe_sample() for synthesizing samples
+ * prior to arm_spe_decode().
+ *
+ * Two reasons for this code logic:
+ * 1. Firstly, when setup queue in arm_spe__setup_queue(), it
+ * has decoded trace data and generated a record, but the record
+ * is left to generate sample until run to here, so it's correct
+ * to synthesize sample for the left record.
+ * 2. After decoding trace data, it needs to compare the record
+ * timestamp with the coming perf event, if the record timestamp
+ * is later than the perf event, it needs bail out and pushs the
+ * record into auxtrace heap, thus the record can be deferred to
+ * synthesize sample until run to here at the next time; so this
+ * can correlate samples between Arm SPE trace data and other
+ * perf events with correct time ordering.
+ */
+ ret = arm_spe_sample(speq);
+ if (ret)
+ return ret;
+
ret = arm_spe_decode(speq->decoder);
if (!ret) {
pr_debug("No data or all data has been processed.\n");
@@ -453,10 +477,17 @@ static int arm_spe_run_decoder(struct arm_spe_queue *speq, u64 *timestamp)
if (ret < 0)
continue;
- ret = arm_spe_sample(speq);
- if (ret)
- return ret;
+ record = &speq->decoder->record;
+ /* Update timestamp for the last record */
+ if (record->timestamp > speq->timestamp)
+ speq->timestamp = record->timestamp;
+
+ /*
+ * If the timestamp of the queue is later than timestamp of the
+ * coming perf event, bail out so can allow the perf event to
+ * be processed ahead.
+ */
if (!spe->timeless_decoding && speq->timestamp >= *timestamp) {
*timestamp = speq->timestamp;
return 0;